Lightweight Carpet Tile and Method

ABSTRACT

A novel carpet tile is provided with a polyurethane adhesive layer resulting in a lightweight product with exceptional dimensional stability.

This patent application claims priority to U.S. Provisional ApplicationSer. No. 62/460,328, filed Feb. 17, 2017.

FIELD OF THE INVENTION

The present invention relates to improved methods for manufacturinglightweight carpet tile products especially suited for the residentialmarket and the structure of those tiles, but also adaptable tocommercial use.

BACKGROUND OF THE INVENTION

The carpet tile market has evolved into distinct categories forcommercial and residential markets. The commercial market for hotels,hospitality facilities, and public buildings is exemplified by hightraffic, mostly foot traffic, but also rolling carts and equipment. Inthis market, there is little demand for plush surfaces that wouldreadily show wear in lanes of traffic. Carpet tiles designed for thecommercial market have evolved into largely a low loop pile surfacecategory or in some cases cut/loop with dense cut pile areas, and thestructure of these tiles is intended to withstand heavy commercial use.Thus, nylon yarns are preferred and are tufted into a primary backing tocreate the greige, and a secondary backing is attached. The secondary oreven a tertiary backing may consist of multiple layers to providedimensional stability and durability under heavy use.

Some carpet tiles are specifically designed for residential use,previously typified by Berkshire Flooring carpet tiles that wereavailable through Home Depot and other direct-to-consumer outlets. Thetiles were inexpensive and typically featured a polyester fiber tuftedto a relatively higher height with a relatively lower stitch densitythan commercial carpets, having a face weight of about 25 ounces persquare yard. The amount of face yarn by weight is not necessarilyparticularly different than face yarn on a commercial carpet tile;however, the weight is often achieved through a higher pile heightrather than closely spacing lower tufts of yarn. After attaching thesecondary backing, the carpet is sprayed with an adhesive and married torelease sheet to provide peel-and-stick functionality. The backing istypically a woven or non-woven fabric, and the residential carpet tileis sufficiently light that it can be cut to fit with relatively ease bya consumer. In the manufacturing process, the light weight product canbe cut by a variety of devices to create the tiles. In contrast, thecommercial carpet tiles have more substantial laminated secondary ortertiary backing layers so that tiles must be die-cut. On-site fittingof commercial tiles may require professional cutting tools to fit thetiles around obstructions or irregular edges.

An aspect of residential carpet tiles that has traditionally added totheir manufacturing cost is the use of latex backing and the cost ofbacking materials. Accordingly, by utilizing a polyurethane rollercoating process to apply a polyurethane adhesive backing to the greige,lightweight nonwoven secondary backings such as nonwoven felt,needlepunch, or relatively light leno weave of slit film and spun olefinyarns fabrics can be used. Thus, cost can be removed from themanufacture of residential carpet tiles, while providing surprisingdimensional stability, tuft bind, and other performance metrics.

SUMMARY OF THE INVENTION

The applicant has developed a process for the application ofpolyurethane coating on greige and the use of inexpensive secondarybackings that are suitable for use with sprayed-on peel-and-stickadhesives that allow the resulting carpet to be easily cut to tiledimensions.

Furthermore, the tile made according to this process and evaluated underASTM D7570, Evaluation of Dimensional Stability of Pile Floor Coverings,has demonstrated minimal expansion or shrinkage under a variety of testconditions. Furthermore, the foaming of the polyurethane backing can becontrolled to provide some cushion without the necessity of attaching aseparate cushion or pad layer to the tile. The placement of the cushionbetween the greige and secondary backing may be particularly helpful inminimizing the creation of visual ledges between tiles as weight isapplied near the edge of one tile but not upon the adjacent tile. Withthe use of appropriate backing fabrics, the polyurethane backing canprovide suitable dimensional stability, and the fabric may bemanufactured with sufficient tuft density, to be suitable for commercialuse, as well.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings which are incorporated and which constitute apart of this specification illustrate an exemplary embodiment of thepresent invention and together with the detailed description set forthbelow explain principles of the invention wherein:

FIG. 1 is a sectional view of an exemplary loop pile carpet tilematerial made that can be manufactured utilizing a polyurethane coatingprocess;

FIG. 2 is a sectional view of an exemplary cut pile carpet tile materialthat can be manufactured utilizing a polyurethane coating process,having a peal and stick adhesive backing and release sheet;

FIG. 3 is a schematic representation of a manufacturing process for thecreation of carpet according to the invention;

FIG. 4 is a schematic representation of the finishing process to convertthe manufactured carpet into adhesive floor tile.

DETAILED DESCRIPTION OF THE INVENTION

A detailed explanation of a polyurethane coating process is set forth inU.S. Pat. No. 7,638,008, which is incorporated herein in its entirety.The roller coating process of this patent and related improvements asdescribed in U.S. Ser. No. 15/782,265, is advantageously used in themanufacture of lightweight carpet products.

FIG. 1 depicts a sectional view of a loop pile carpet tile 40 withlooped bights of yarn 41 penetrating a backing material 42, bound inposition with a polyurethane adhesive layer 43, and an attachedsecondary backing of 44. The carpet density can be substantially lessthan 3000, or less than 2500, or even less than 2000. Carpet density iscalculated using the following formula:

Carpet face weight×36/carpet pile height=density, measured in ounces percubic yard

The pile height is the length of the fiber from tip to the carpetbacking. In the above formula, pile height should be represented as afraction of an inch, reflected in decimal format. For example, a pileheight of half of an inch would be represented as 0.5; a pile height ofa quarter of an inch would be 0.25.

For commercial application, the pile height would typically be reduced,the spacing of stitches in the carpet would be more compressed, and thesecondary backing 44 would be selected for greater stability than inresidential applications. An additional tertiary backing could even beapplied to maximize stability, durability, or other metrics.

FIG. 2 is a sectional view of a cut pile carpet tile 45 with cut bightsof yarn 46 tufted through primary backing 47 bound in position bypolyurethane adhesive layer 48, secondary backing material 49, pressuresensitive adhesive layer 50, and release sheet 51.

It will be understood that some foaming of the polyurethane adhesivelayers, 43, 48 can provide cushioning, or an additional layer ofmaterial can be adhered to the exemplary carpets of FIGS. 1 and 2 toprovide a cushioned carpet tile product. Such additional cushioninglayer would commonly be affixed below the secondary backings 44, 49. Forcommercial or heavy-duty applications, a tertiary backing may even beapplied to the cushion layer. Commercial or hospitality sizes may alsoneed to be more varied, ranging from 9 to 12 inches long by 36 or 48inches in length to 36 inch square configurations

The schematic representation of FIG. 3 illustrates an exemplaryconstruction for application of polyurethane adhesive material andprovides a method to adjust the distance between the polyurethaneapplication rollers 23, 26 and marriage point with a secondary backing.Specially, the unbacked greige 11 is passed through a tenter frame 91and J-box 92 to condition and control the greige prior to application ofthe polyurethane material. The polyurethane material is prepared with asubstantial load of filler material such as calcium carbonate tominimize cost. From 250 to 700 parts of filler can be used for every 100parts of polyol, where polyol and isocyanate are the criticalpolyurethane forming ingredients.

The greige 11 proceeds past application rollers 23, 26 and polyurethaneis pressured into the greige by upward pressure from support rollers,and particularly the pressure applied by adjustable roller 127 tocommunicate pressure upward against the greige and effect the amount ofpolyurethane material being applied while imbedding the viscouspolyurethane into the fibers of the primary backing. The polyurethanematerial is applied at a weight of between 14 and 45 ounces per squareyard, and preferably less than 25, or even 20, ounces per square yardfor residential carpet tile. Weights of 24 to 45 ounces of material arepreferred for commercial or hospitality carpet tile. A moveable tenterroll 147 is adjustable between a low position 47 and a high position 247shown in phantom, and the illustrated intermediate position 147 to allowthe length of coated greige intermediate the application rolls 23, 26and nip rolls 160 a, 160 b at the marriage point with secondary backing55 to be increased or decreased and thereby effect the completeness ofthe reaction of the polyurethane material at the marriage point. Eithernip rolls 160 a, 160 b or subsequent rubber coated pressure rolls 66 a,66 b should be pressure controlled to ensure complete marriage of thesecondary backing to the coated greige 11. Residential carpet tile willtypically use an economical secondary backing material such as nonwovenfelt, needlepunch, or a leno weave of slit film and spun olefin yarns(Action Bac®) fabrics.

Thereafter the carpet passes around first heat can 40 and second heatcan 41 to iron the secondary backing 55 to the greige and speed thecuring process. The carpet then goes through accumulator 190 to roll-upas the finished carpet product 200.

As shown in the schematic representation of FIG. 4, the carpet withsecondary backing applied 200 may proceed through an additional step ofapplying adhesive from sprayer 121 to affix a cushioning layer 155 atmarrying roller 260 all shown in phantom), and also proceeds through theapplication of a pressure sensitive adhesive from sprayer 221 and arelease sheet 255 using marrying roller 261 to insure uniformity. Thenthe adhesive backed carpet material proceeds to cutting station 270 andis cut into modular pieces, typically 2 foot squares (though smallersizes down to about 18 inch squares are also useful), by a cuttingprocess. In the case of commercial tile, it is frequently necessary toemploy a die-cut process, however with light weight residential tile,other cutting processes including the use of rotary blades 271, cuttinglongitudinally, and blades 272 cutting laterally, or cutting wires maybe employed. The resulting carpet tiles 40 are boxed 280 and shipped forsale. Boxes may preferably contain between about 8 and 24 carpet tiles.

The resulting carpet tiles exhibit unusual dimensional stability for atile product not including a rigid backing layer such as fiberglassreinforced fabric. In ASTM D7570 testing such lightweight polyurethanebacked tile typically provide variations of less than 0.5% on mostmeasurements during varied exposures to conditions of heat and moisture.The typical measurements are taken for:

a) Original measurement in machine direction

-   -   b) Original measurement in cross direction    -   c) Two hours in drying oven at 60° C.    -   d) Two hours submerged in 0.1% detergent solution at 20° C.    -   e) Twenty four hours in drying oven at 60° C.    -   f) Forty eight hours conditioning at 20° C. and 65% relative        humidity

In many instances, variations for measurements (c)-(f) may vary lessthan 0.3%, or even 0.1%. In commercial applications, such a rigidbacking layer may be added to provide even greater durability andachieve variations of less than 0.05%.

Although a preferred embodiment of the present invention has beendisclosed herein, it will be understood that various substitutions andmodifications may be made to the disclosed embodiment described hereinwithout departing from the scope and spirit of the present invention asrecited in the appended claims.

Having thus set forth the nature of the invention, what is claimedherein is:

1. A rectangular carpet tile product as comprising a greige with aprimary backing material having tufted face yarns extending from a faceside and an opposite backstitch side; a single layer of polyurethanecompound between the backstitch side of the greige and a front side of asecondary backing material; a pressure sensitive adhesive on an oppositeback side of the secondary backing material; and a release sheetcovering the pressure sensitive adhesive; wherein the carpet tile isdimensionally stable and has edges with a length of about 18 to 24inches.
 2. The carpet tile of claim 1 wherein the tufted face yarns areselected from the group of polyester yarns and polypropylene yarns. 3.The carpet tile of claim 1 wherein the secondary backing material isselected from the group of woven fabrics, nonwoven felts, needlepunchfabrics, and leno weave fabrics.
 4. The carpet tile of claim 1 whereinthe polyurethane compound comprises polyol, isocyanate, and filler, andthe ratio of filler to polyol is greater than 2.5 to
 1. 5. The carpettile of claim 1 wherein the polyurethane compound is applied at a rateof between 14 and 45 ounces per square yard.
 6. The carpet tile of claim6 wherein the polyurethane compound is applied at a rate of less than 25ounces per square yard.
 7. The carpet tile of claim 1 wherein the carpetdensity is less than
 2000. 8. The carpet tile of claim 5 wherein thepolyurethane compound is foamed.
 9. The carpet tile of claim 1 whereinthe variations in ASTM D7570 testing are less than 0.5%.
 10. Arectangular carpet tile product as comprising a greige with a primarybacking material having tufted face yarns extending from a face side andan opposite backstitch side; a single layer of polyurethane compoundbetween the backstitch side of the greige and a front side of asecondary backing material; the polyurethane compound comprising polyol,isocyanate, and filler, with the ratio of filler to polyol is greaterthan 2.5 to 1, and the polyurethane compound applied to the backstitchside at a rate of between 14 and 45 ounces per square yard; wherein thecarpet tile is dimensionally stable.
 11. The carpet tile of claim 10wherein the secondary backing material is selected from the group ofwoven fabrics, nonwoven felts, needlepunch fabrics, and leno weavefabrics.
 12. The carpet tile of claim 10 wherein the carpet density isless than
 2500. 13. The carpet tile of claim 10 wherein the variationsin ASTM D7570 testing are less than 0.3%.
 14. The carpet tile of claim10 wherein a cushioning layer is affixed to an opposite bottom side ofthe secondary backing.
 15. The carpet tile of claim 10 wherein atertiary backing is affixed below the secondary backing.
 16. The carpettile of claim 15 wherein the variations in ASTM D7570 testing are lessthan 0.1%.
 17. The carpet tile of claim 15 wherein the carpet density isless than
 3000. 18. The carpet tile of claim 10 having edges withlengths of about 9 to 48 inches.
 19. The carpet tile of claim 10 whereinthe tufted face yarns are nylon.
 20. The carpet tile of claim 10 whereinthe polyurethane compound is applied at a rate of between 24 and 45ounces per square yard.